In just a week, the U.N. plans to hold Syrian peace talks in Switzerland. In the meantime, the U.S. is leaning hard on opposition leaders to attend and talk face-to-face with a government they've been fighting hard to topple. Secretary of State John Kerry has been in meetings for the past two days in Paris, laying the groundwork for the conference.

He and his Russian counterpart are calling on the warring sides to open humanitarian aid corridors, and to take other steps to improve the atmosphere for negotiations.

But as NPR's Michele Kelemen reports, the odds of success are long.

MICHELE KELEMEN, BYLINE: International envoy Lakhdar Brahimi has been trying for many months to bring to the warring parties to the negotiating table. Now the date is in sight, January 22nd, and he's urging everyone - particularly the government of Syria - to make humanitarian gestures and ease the suffering of millions of people.

LAKHDAR BRAHIMI: Prisoner exchanges, humanitarian access and also a ceasefire as wide as possible, but even local ceasefires will be welcome.

KELEMEN: That idea of local ceasefires is something he discussed in Paris with Secretary of State John Kerry and Russia's Foreign Minister Sergei Lavrov. Kerry says there is an urgent need for a ceasefire in Aleppo. And more humanitarian access to other cities that are being pounded by the regime.

SECRETARY JOHN KERRY: There should be no further delay in our judgment in ending the aerial bombardment of children, civilians, and the use of starvation as a weapon of war. We believe the basic disregard for human rights and human dignity that we are witnessing in the area needs to come to an end.

KELEMEN: Lavrov, whose government backs the Syrian regime, says Damascus is ready to open aid corridors including to the suburbs of the capital, where 160,000 people have been trapped by the fighting. But speaking through an interpreter, Lavrov made clear that the opposition needs to do its part. And he raised concerns about the extremists in their ranks.

SERGEY LAVROV: (Through translator) We do not want a ceasefire which would be used by terrorists groups because that would be against the interests of everyone.

KELEMEN: Lavrov and Kerry couldn't paper over their different views of the conflict in Syria. That was true also when it came to the issue of Iran. The Russian foreign minister says he thinks Iran should be invited to the peace conference in Switzerland next week despite U.S. concerns.

LAVROV: (Through translator) One cannot be influenced by ideological sentiments so much that it harms the interest of the cause.

KELEMEN: Kerry says he's not driven by ideology but by the fact that Iran hasn't agreed to the basic idea of the conference: negotiations on a transitional government for Syria, one that the U.S. believes will not include Bashar al-Assad. And Iran, Kerry says, is a party to the conflict, supplying arms to the government and backing Hezbollah fighters who have poured into Syria from Lebanon to bolster the Assad regime.

KERRY: I invite Iran today to join the community of nations, the 30 nations that are already prepared to come, and be a constructive partner for peace. That's the invitation.

KELEMEN: Brahimi, the diplomat who will be chairing the peace conference tried hard to remain above this dispute, saying he's still working with the U.S. and Russia on the final guest list, though he does think Iran and anyone with influence should be there.